- Class 1: Slow Rate of Evaporation (Least Amount of Water, absorption and evaporation):
Water losses that affect only part of a room or area is wet or larger areas containing materials that have absorbed minimal moisture. Little or no wet carpet and/or cushion is present.
- Class 2: Fast Rate of Evaporation (Large amount of water, absorption and evaporation):
Water losses that affect the entire room or more is affected. Carpet and cushion (pad) may be wet. Water has wicked up walls less than 24 inches. There is significant moisture remaining in structural materials; (e.g. plywood, particle board, structural wood, VCT, concrete and substructure soil).
- Class 3: Fastest Rate of Evaporation (Greatest amount of water, absorption and evaporation):
Fully involved. Water may have come from overhead. Ceilings, walls, insulation, carpet, cushion, and subfloor in virtually the entire area are saturated.
- Class 4: Specialty Drying Situations
These losses involve wet materials with very low permeance/porosity (e.g. hardwoods, plaster, brick, light weight concrete, stone and crawlspaces). Typically, there are deep pockets of saturation, which require very low specific humidity. These situations MAY require longer drying times and special methods.
Classes of Water LossThe term "Class" of water loss is the initial determination of the amount of water and the likely or anticipated rate of evaporation. The basis for the distinction between the Classes of water intrusion are: the amount of materials, the moisture content of the materials involved, the rate of evaporation of the materials and where the materials are located within a structure. This information should be gathered during the inspection of the affected areas. The classes of water are divided into the following ways: